Method of making closure for containers



Nov. 5, 1968 J. M. DE VOE METHOD OF MAKING CLOSURE FOR CONTAINERS 2Sheets-Sheet 1 Filed Dec. 12, 1966 IN VE N TOR John M. DeVoe By 69mm,Mm; 5%,{604

ATTORNEYS Nov. 5, 1968 J. M. DE VOE 3,408,902 I METHOD OF MAKING CLOSUREFOR CONTAINERS Filed Dec. 12, 1966 2 Sheets-Sheet 2 ?Fig.3

INVENTOR John M. DeVoe y fla/zi f/swnliaw ATTORNEYS United States PatentFiled Dec. 12, 1966, Ser. No. 601,136 Claims. (Cl. 931.3)

This invention relates to closures for containers and more particularlyto fluid-tight or moisture-proof closures formed of layers of paper andmetal foil.

Moisture-proof or vap0r-proof containers have been made by producingcardboard or paperboard containers and lining them with metal foil. Insome of the prior containers the foil lining has been attached to thecardboard by gluing, but that has'not provento be a satisfactory way ofproducing the closures for such containers. A closure in which thelayers are glued together is not sturdy, and it tends to lose its shape,which weakens the closed container, and it also causes the closure tofit less snugly against the container walls than is desired. A tigh fitbetween the closure and the container is particularlv important in amoisture-proof container, and the lid should continue to hug thecontainer tightly even after it has been removed from the container andreplaced on it several times.

An object of this invention is to provide a container closure that isstrong and sturdy, and which fits tightly on the container. A furtherobject is to provide a container closure that will retain its desirablecharacteristics after repeated removal from the container andreplacement thereon. A further object of the invention is to provide asimple and inexpensive method of making such closures. These and otherobjects will be in part obvious and in part pointed out below.

Stated in somewhat simplified form, this invention comprises formingcontainer lids from paper and foil layers, e.g., in a punch press, whilethe paper is damp, and in such :a way that a number of small, sharpridges or barbed fins are created in the foil against the paper and areforced into the surface of the paper, after which the paper is shrunk.The ridges or fins are intimately interlocked into and are gripped bythe fibers of the paper so that the lid is sturdy and compact. Hence, anintegral lid is formed of the layers of paper and foil without the useof adhesive.

In the drawings:

FIGURE 1 is a perspective view, with a portion cut away, of a containerwith closures made in accordance with the present invention;

FIGURE 2 is a cross-sectional view of a portion of the container shownin FIGURE 1, taken along line 22;

FIGURE 3 is a cross-sectional view of a punch press for producing theclosure shown in FIGURE 1;

FIGURE 4 is a plan view of the die portion of the punch press shown inFIGURE 3, taken along line 4-4 in FIGURE 3; and

FIGURES Sand 6 are similar to FIGURE 3, except that they show the punchpress in different stages of its cycle, and they are schematic in thatthey show a single sheet of the paper and foil.

FIGURES 7 and 8 are detailed sectional views of the completed closure.

Referring to FIGURE 1 of the drawings, a cylindrical container 2comprises a side wall 4 and end closures 6 and 8. End closure 6 (seealso FIGURE 2) is in two layers, a paper layer 10 and a metal foil layer12. Side wall 4 is of similar construction, comprising both a paperlayer 14 and a foil layer 16. Each of the layers of closure 6 is asingle circular piece or disc which has been shaped to form a shallowcylinder with a flat, disc-like end wall 3,408,902 Patented Nov. 5, 196818 and a cylindrical side wall formed by portions 19 and 21,respectively, of the paper and foil layers. The internal diameter ofside wall 20 is such that it fits snugly against the side wall 4 of thecontainer. The portion of the sidewall 20 that has been cut away toexpsoe the cylindrical portion 21 of the foil layer 12 is enlarged inFIG- URE 8, and shows a great many small ridges 22 in portion 21. Theseridges project into and interengage with the paper layer portion 19,creating a strong bond between the two layers and forming an integralmechanically-lamb nated wall.

FIGURES 3 through 6 show the portions of a standard punch press thathave been adapted to produce closure 6 in accordance with the presentinvention. The punch press 24 includes a fixed die assembly 26 and amovable punch assembly 28 which moves vertically to engage the die 26 asshown in FIGURES 5 and 6.

Referring to FIGURE 3, the die assembly 26 includes a shaft 30 uponwhich components of the die assembly are mounted. Attached in astationary manner to shaft 30 are: a die shoe 32; a center post 34; acircular pad 36; and, a peripheral cutting ring 40. Pad 36 presents aflat upper surface 35 except that it -has a raised rim portion whichpresents an elevated peripheral edge surface 37. Edge surface 37 is aninverted frusto-conical surface so that it slopes toward the center ofpad 36. Circular pad 36 is surrounded snugly by a draw ring 38 which hasfrusto-conical top surface 39, and (see also FIGURE 4) is mountedresiliently in a manner later to be described. Draw ring 38 issurrounded snugly by cutting ring 40, the inner edge of the top of whichis a cutting edge 42.

Draw ring 38 is adapted to slide vertically inside cutting ring 40 alongthe outside of pad 36 and central post 34 with its upward motionlimited, however, by the engagement of a flange 44 on the draw ring witha horizontal edge surface 45 of ring 40. Draw ring 38 is supported by aplurality of rods 48, the upper ends of which are fixed to the drawring, and each of which is rigidly attached at its lower end to a ring49 that slides on shaft 30. A heavy compression spring 50 presses upwardon ring 49 urging draw ring 38 toward the position shown. Spring 50rests upon a disk 51, which is supported adjustably on shaft 30.

The punch assembly 28 of the punch press is located above the dieportion 26 and moves downwardly and engages the die assembly in thecourse of each closureforming cycle of the machine. Punch assembly 28comprises: a punch head a punch holder 52 which is mounted in a fixedmanner on head 55; and, a punch 54 which has a top flange 57 by which itis rigidly affixed to holder 52 by a clamp ring 56. Punch 54 is acircular ring which is similar to draw ring 38 and has the same generalouter and inner radii except for the flanges 44 and 57. Punch 54 ispositioned above the draw ring and has a bottom frusto-conical surface53 which is identical with surface 39 of the drawing and forms a cuttingedge which mates with cutting edge 42 of the stationary cutting ring 40.As the punch assembly moves downwardly to engage the die assembly, punch54 enters the space between pad 36 and cutting ring 40, and surface 53engages surface 39 so that the continued movement pushes draw ring 38down, overcoming the upward force of spring 50. Also, as will beexplained below, the cutting edges interengage to cut a disc portionwhich is formed into a closure 6.

Slidably mounted within punch ring 54 and normally resting against punchholder 52 is a punch pad 58, which is of substantially the same radiusas pad 36. Punch pad 58 has a bottom surface which is flat except thatthe edge is somewhat beveled to form a frusto-conical edge surface 60that is adapted to mate with the raised edge surface 37 of pad 36. Punchpad 58 is rigidly mounted on a shaft which is surrounded by a co 7 Uspring 6fby which tlie shaft and the punch pad are normally held in theposition shown in FIGURE 3. Punch pad 58 contains a plurality of airvents 64 which are normally closed by valves 63 which are urged toclosed position by springs 65. However, the vents are opened when theprojecting noses of valve 63 are pressed upwardly. I

The sheets of paper 66 and foil 68 from which the closures are producedare drawn through the punch press from left to right with foil sheet 68passing just above the upper surface of die assembly 26 and with thepaper sheet 66 directly above the foil sheet. The paper and foil P estsheets are guided in this movement by a metal plate 70 located a shortdistance above the upper surface of the die assembly 26 and forming anarrow horizontal slot 72, through which the paperand foil sheets pass.A circular hole 74 in plate 70 is of a size to permit the punch 54 topass through it. v

In the illustrative embodiment, the foil is a thin steel foil, andthepaper is kraft lined can bottom stock of .03 inch thickness. Prior tofabrication the paper is softened by soaking it with a light soapsolution. In practice, each day the paper which is to be used thefollowing day is wetted on a rewinder onto rolls which are storedovernight in closed containers. Hence, the paper is relatively soft,although it retains sufficient strength to permit fabrication at acommercially satisfactory rate.

The paper and foil sheets advance step-by-step with each step being fora set distance during the sheet feeding portion of each cycle when thepunch assembly is in the position shown in FIGURE 3, and remainingstationary when the punch is engaging the die as shown in FIG- URES 5and 6.

The operation of the punch press is illustrated in FIG- URES 5 and 6 andis as follows: As the punch head moves downwardly, punch ring 54 forcesthe paper and foil sheets downwardly to cutting ring 40 and thence asthe punch moves past the cutting edge 42 of ring 40 the punch cooperateswith the cutting edge to cut both sheets to produce a circular piece ordisc from each of the sheets. The two discs thus formed are unattachedat this time and by the further cooperative action of the punch and dieassembly they are formed into a container closure. As the punch assemblycontinues to move downwardly, the peripheral portion of each of thesediscs is trapped between the upper surface 39 of draw ring 38 and thelower surface 53 of punch ring 54. However, as the punch continues itsdownwardly motion, forcing the draw ring down before it, the peripheralportions of the paper and foil discs slip between the punch and drawrings and are reformed to a cylindrical form so that they assume avertical position between the inner surface of punch ring 54 andsidewall of pad 36. The forming of the side walls of the closure in,thismanner produces the foil ridges 22 and they are embedded in the surfaceof the paper, the space between pad 36 and punch ring 54 being onlylarge enough to accommodate the layers in this manner.

The inverted frusto-conical edge portion of pad 36 (FIGURE 6) cooperateswith the peripheral surface of pad 58 to form the foil into a firmcorner which acts as a rigid rim interconnecting the disc-like foilendwall with the cylindrical foil side wall. The innner surface of the foilis extremely smooth, with only small lines which are formed by theproducing of the external ridges 22. The forming involves bending theblanks around the raised periphery of pad 36 (see FIGURE 5) as the punchring pushes the peripheral portions of the blanks downwardly. Theperipheral portions are held in somewhat frusto-conical shape by theclamping action between the punch ring and the draw ring 38, and. aregradually drawn into the cylindrical shape. The drag caused by theaction of the punch ring upon the blanks produces a peripheral tensionupon the central disc portions of the blanks so that they are heldsomewhat tauhAt the end of the downward movement of the p un cli ring,pad

58 cooperates in producing the final smooth corner. It should be notedthat FIGURES 5 and 6 are somewhat schematic with respect to dimensionsand the relative positioning ofthe parts.

As pad 58 approaches pad 36, the trapped air lifts valves 63 and the airescapes through vents 64. When the'punch head reaches the bottom of itsstroke, the pads press the paper and foil layers together. As the punchhead begins its upward motion, the completed closure is pushed from itsposition on pad 36 by the draw ring 38 which moves upwardly with thepunch head and which engages the'bottom edge of the cylindrical closurewall and pushes the closure upwardlyQThus, the completed closure remainswithin the punch ring 54 beneath the punch pad 58 after thedisengagement of the die and punch portions of the press. I

When the punch ring 54 moves upwardly towards the position of FIGURE 3,punch pad 58 is pushed downwardly against the action of spring 62 toeject the closure from the punch ring. This is caused by a knocker (notshown) driving the central supporting shaft 59 downwardly against theaction of its spring 61. The sheets 66 and 68 of the paper and foil arethen advanced another step from their supply rolls, and the punching andforming operation is repeated. While only one die assembly is shown inthe drawings, it is understood that several such assemblies are mountedtogether on shaft 59, and are operated simultaneously.

Subsequent to the forming of the closure as discussed above, the paperis dried so that it shrinks around the foil liner. The shrinking urgesthe paper fibers in around the ridges 22, and the paper is hardened sothat the closure is an integral sturdy structure. The shrinking of thepaper draws it tightly around the corner edge of the foil liner in asmooth corner from the fiat-top surface.

As has been pointed out above, sheet 68 in the illustrative embodimentis thin steel foil. In one particular example, the steel is tin-platedsteel foil of .02 inch thickness. The working of the metal foil produceswork hardening so that it has superior characteristics. Tests indicatethat container closures made with such foil and the paper sheet referredto above are superior to metal lids from various standpoints, includingresistance to shock. Also, such closures are superior from thestandpoint of being thoroughly satisfactory over extended periods of useduring which a closure may be removed from its container and replacedmany times. The thin steel cylindrical wall and the rigid corner haveresiliency and tend to retain the original shape. The paper providesimpact protection and causes the closure to hug the container wall.

It has been found that hard aluminum foil also gives very satisfactoryresults in place of the steel foil. The invention contemplates thatvarious types of paper board may be used provided they are not waterrepellent or water proof. The illustrative embodiment of the inventionis a closure for small containers which may be used for snuff. However,it is contemplated that the invention includes the production of othercomponents.

I claim:

. 1. In the method of producing container closures of the type having anend wall and a peripheral side wall structure, the steps of, wetting asheet of kraft-coated paper for a sufficient time to soften it,positioning the sheet in a die assembly with a sheet of metal foil,cutting a blank from each of said sheets, subjecting the sheets to asimultaneous soft forming operation by pushing the peripheral sidewallof the paper blank to thereby form the peripheral portions of the paperblank and the foil blank into an integral side wall structure against aninner surface which causes folds in the metal foil to be projectedoutwardly and to be embedded in the softened paper, and drying the paperto cause it to shrink and harden.

2. The method as described in claim 1 which includes,

forming a corner structure interconnecting the end wall of the closureto the side wall structure by pressing the blanks together at theperiphery of the end wall between inverted frusto-conical die surfaces.

3. The method as described in claim 1 wherein the foil is tin-platedsteel foil having a thickness of the order of .02 inch and the paperhaving a thickness of the order of .03 inch, and wherein the containerclosure has a disclike end wall and a cylindrical side wall.

4. The method as described in claim 1 wherein the peripheral portions ofthe blanks are held between annular surfaces and are formed into acylindrical side wall starting from the peripheral edge of the end wallof the closure whereby the metal foil is Worked progressing radiallyoutwardly.

5. In the art of producing components from blanks of water-softenedpaper and metal foil with each component having an end wall portion anda peripheral side wall structure, the steps of, pressing the peripheralportions of the blanks together from the vicinity of the outer peripheryof the end wall portion to the outer edges of the blanks, rigidlysupporting the end wall portion, forming the peripheral side wallstructure starting at the periphery of the end wall portion by aradial-outward progressive softforming operation whereby the metal foilis worked and ridges are formed in the foil which extend radiallyoutwardly along the adjacent surface of the paper and are embedded inthe paper, and drying the paper to cause it to shrink and harden.

References Cited UNITED STATES PATENTS 2,832,522 4/1958 Schlanger 93-1.3XR

BERNARD STICKNEY, Primary Examiner.

1. IN THE METHOD OF PRODUCING CONTAINER CLOSURES OF THE TYPE HAVING ANEND WALL AND A PERIPHERAL SIDE WALL STRUCTURE, THE STEPS, OF, WETTING ASHEET OF KRAFT-COATED PAPER FOR A SUFFICIENT TIME TO SOFTEN IT,POSITIONING THE SHEET IN A DIE ASSEMBLY WITH A SHEET OR METAL FOIL,CUTTING A BLANK FROM EACH OF SAID SHEETS, SUBJECTING THE SHEETS TO ASIMULTANEOUS SOFT FORMING OPERATION BY PUSHING THE PERIPHERAL SIDE WALLOF THE PAPER BLANK TO THEREBY FORM THE PERIPHERAL PORTIONS OF THE PAPERBLANK AND THE FOIL BLANK INTO AN INTEGRAL SIDE WALL STRUCTURE AGAINST ANINNER SURFACE WHICH CAUSES FOLDS IN THE METAL FOIL TO BE PROJECTEDOUTWARDLY AND TO BE EMBEDDED IN THE SOFTENED PAPER, AND DRYING THE PAPERTO CAUSE IT TO SHRINK AND HARDEN.